This invention relates generally to electronic shelves and the routing of light conducting fiber that terminates on circuit boards contained in the electronic shelf. More specifically, this invention relates to the routing of light conducting fibers that must exit near the front faceplate of circuit boards in an electronic shelf where a narrow spacing between the front faceplate and the front of the cabinet housing the electronic shelf prevents the light fibers from exiting perpendicular to the front faceplate.
Electronic shelves are generally well-known that contain a plurality of circuit boards. Typically each circuit board is mounted in the electronic shelf by sliding it along a slot until the back edge of the circuit board engages a connector such as mounted to a backplane. Each circuit board contains a front faceplate that extends perpendicular to the plane of the circuit board. Each front faceplate is dimensioned to form a contiguous front panel along the electronic shelf when all slots within the shelf are occupied by circuit boards. This is advantageous since the front panel formed by the front faceplates of the circuit boards minimize unwanted radio frequency radiation that may be generated by the circuit boards and also form a substantially airtight seal along the front of the electronic shelf so that air used for forced-air cooling of the components on the circuit boards is not unintentionally lost through the front faceplates.
The high bandwidth available for conveying information by modulated light conducted along light carrying fiber may be desirable, if not required, to carry communications from a circuit board in an electronic shelf to another circuit board or other external electronic devices. There are significantly more conditions that must be met when connecting fiber to a circuit board as opposed to connecting metallic conductors to a circuit board. Fibers are normally connected to a circuit board by manual insertion involving a push-on, bayonet style or threaded end connector. This makes connecting fibers to the rear edge of the circuit board substantially more difficult especially when the circuit board is to be mounted within an electronic shelf. In such a situation, the fibers must either be attached prior to the insertion of the circuit board into the electronic shelf resulting in a substantial length of fiber that must be placed/dressed within the shelf at the time of mounting the circuit board, or manual access must be provided at the rear of the electronic shelf to permit the manual connection of the fiber to a corresponding receptor on the circuit board.
Providing fiber connector receptacles on the front faceplate of circuit boards provides for relatively easy installation and connection of fibers perpendicular to the front faceplate of the circuit boards. This provides a solution to the difficulties encountered when fiber connections are attempted at or near the rear of the circuit boards. However, this front mounting technique places certain requirements on the electronic shelf. A significant requirement is that there can be no front cover or other obstruction near the front faceplate of the circuit boards when seated within the electronic shelf. The fiber cannot be bent at a right angle and requires a minimum bend radius be maintained to prevent damage to the fiber and to avoid adversely affecting the light transmission characteristics.
Electronic shelves may not be designed to accommodate circuit boards that require fiber connections to the front of the circuit boards. For example, electronic shelf standards such as proposed by the Advanced Telecom Computing Architecture (AdvancedTCA) make it difficult, if not impossible, to accommodate circuit boards that require fiber connections to the front faceplates where the circuit board is long enough to cause its front faceplate to be only a short distance from the front door of the cabinet that houses the electronic shelf. This electronic shelf standard requires a front door that is spaced parallel to and only 95 millimeters from the front panel of circuit boards. When this front door is closed, it will make the routing/dressing of fiber extending perpendicular from the front faceplate of circuit boards difficult. Thus, there exists a need for an improved technique for managing the routing of fiber at the front of a circuit board to be housed in an electronic shelf with a nearby front door or other nearby physical obstruction.